Public Safety Tips
Aluminum Wiring
The facts about aluminum wiring in the home
Do you have aluminum wiring in your home?
How to find out! It is estimated that there are over 450,000 homes in Canada that are wired
with aluminum wiring. How do you find out what type of wiring has been installed in your home?
Well, if you weren't told when the sale was made, you can probably check the wiring yourself.
This can usually be done by looking at the electrical wiring, either between the open floor joists,
in the basement, up in the attic, or at the service panel. If the wiring is aluminum and was
manufactured before May 1977, the outer covering of the cable will be marked, at least every 12
inches, with the word ALUMINUM, or an abbreviation, ALUM, or AL. If the cable was
manufactured after May 1977, the marking may be either ALUMINUM ACM, ALUM ACM, or AL
ACM.
Where a home has an electrical range, dryer, or other equipment using heavy electrical loads,
there will be a mixture of wire sizes installed in the home. Larger gauge wire will be used for
feeding the heavy loads, while the smaller gauge will supply electricity to the lights and wall
plugs.
You may find that aluminum wiring has been used for all the wiring, including the heavy
appliances, or alternatively, copper wiring may have been used throughout the residence.
However, sometimes a mixture of aluminum and copper wiring is installed. If you find that the
wiring installed for lights and wall plugs is aluminum, then it's important that the CO/ALR
devices, described below, be used for replacement of wall switches and receptacles.
Aluminum wiring is safe if properly installed
In 1977, the Government of Ontario established a Commission of Inquiry on the use of
aluminum wiring in the home. Following a thorough investigation, which included hearings and
testimonies conducted over a period of 18 months, the Commission recommended that
aluminum wiring should continue to be authorized for residential use.
Use only CO/ALR wall switches and receptacles
If your home has aluminum wiring and you need to replace a switch or wall receptacle,
the replacement device to install should be of a type that is specifically approved for use
with aluminum wiring. Devices approved for the use bear the marking "CO/ALR". This means
"Copper Aluminum Revised" to differentiate these devices from earlier models. The CO/ALR
marking identifies the equipment as having been tested and found suitable for use with
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aluminum or copper wiring by the Canadian Standards Association (CSA), a standards
organization whose certification is accepted by inspection authorities across Canada.
Why is it important to install only CO/ALR devices?
One of the reasons is that when the insulation is stripped from aluminum wire and the wire is
exposed to air, an insulating film immediately forms on the wire. This means that a poor
connection and overheating may result at the switch or receptacle unless the terminal or the
device is built with the right contacts designed to break through the film and ensure a good
connection at the device. Devices marked CO/ALR are specifically designed and approved to
ensure a good connection through the use of a larger contact area and compatible materials.
When connecting to switches and receptacles, the wire should be formed in a clockwise
direction around the screw into three fourths of a complete loop.
Wire connectors
When buying wire connectors for connecting aluminum wires, purchase those
specifically certified for use with aluminum wiring.
Marking on the packages will indicate if the connectors are suitable for connection of aluminum
to aluminum wire, aluminum to copper wire, or copper to copper wire.
When connecting solid aluminum wire to stranded wire, "Special Service" connectors are
recommended. These should also be used with baseboard heaters, hot water tanks and similar
types of cycling loads. A number of manufacturers make these heavy duty connectors with
contrasting coloured insulating caps, such as purple or brown, for easy identification.
Please Note: For devices other that switches and standard receptacles, the marking, which
indicates that equipment is suitable for use with aluminum wiring, is CU-AL. This marking would
appear on circuit breakers, packages for wire connectors, etc.
Installing aluminum wiring
ALERT
Because of the specialized knowledge and techniques required for working with aluminum
wiring, it is recommended that it be installed only by qualified electricians.
If you notice any of the following conditions in your home, the causes should be investigated:
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warm faceplates on switches or receptacles;
strange or distinctive odours in the vicinity of receptacles or switches;
persistent but intermittent flickering of lights that can't be traced to appliance or other
external causes; and
unusual static on radio or television.
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For more information:
For assistance regarding other aspects of an aluminum wiring installation, check with the safety
officer in your area. A number of cities and districts in B.C. maintain their own electrical
inspection service. Please see the list for these electrical jurisdictions.
A booklet providing general information regarding residential electrical installations, titled
"Electrical Safety Homeowner Information Guide" is available at any British Columbia Safety
Authority or at Government Agent offices that issue electrical permits.
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